GMBS is a heterobifunctional amine to sulfhydryl crosslinking reagent.GMBS contains one NHS ester group and a maleimide reactive group at each end of an aliphatic 5-atom spacer.The NHS ester groups readily react towards primary amines at pH 7-9.The maleimide group reacts towards sulfhydryl (or thiol) groups at pH 6.5-7.5.GMBS is not water soluble and must be dissolved in an organic solvent such as DMSO or DMF prior to use.